Question

我正在尝试获取一个类赋值的函数，但是当程序遇到有问题的特定行时它会消失，并且此行之后不执行任何操作。程序没有锁定，只是当前的执行路径死了。

我已经尝试过运行调试，但同样的情况也是如此。一旦我点击应该从存储在Arraylist元素中的对象调用函数的链接，应该调用的实际函数的断点不会被击中而且不会再发生任何事情。

Public Structure Appliances

    ' Create New Appliance object
    Public Sub New(name As String, pusage As Double)
        aName = name
        aPUsage = pusage
    End Sub

    ' Create New Washer Object
    Public Sub New(name As String, pusage As Double, wusage As Double)
        aName = name
        aPUsage = pusage
        aWUsage = wusage
    End Sub

    ' Functions
    Public Function getAName()
        Return aName
    End Function

    Public Function getAPUsage()
        Return aPUsage
    End Function

    Public Function getAWUsage()
        Return aWUsage
    End Function

    Dim aName As String ' Appliance Name
    Dim aPUsage As Double ' Appliane Power Usage
    Dim aWUsage As Double ' Appliance Water Usage

End Structure

...

Public Class Form1

...
    Dim appList As New ArrayList() ' Create an arraylist appliance objects
    Public appTemp As Appliances ' To store appliance objects until they can be added to the arraylist

...
    Private Function getAppInfo()
        getAppInfo = Nothing

        Do While fInStream.Peek() <> -1

            s = fInStream.ReadLine() ' Get a line from the file and set s to it

            Dim words As String() = s.Split(New Char() {","c}) ' Split the line contents along commas and set those parts into words

            words(0) = words(0).Replace("_", " ") ' Reaplce underscores with spaces

            If (words.Count = 3) Then ' If words contains the washer appliance
                appTemp = New Appliances(words(0), Double.Parse(words(1)), Double.Parse(words(2)))
                appList.Add(appTemp)

            Else ' For all other appliances
                appTemp = New Appliances(words(0), Double.Parse(words(1)))
                appList.Add(appTemp)

            End If

        Loop
    End Function

    Private Function setUsage(name As String)
        setUsage = Nothing

        ' Find appliance
        For i = 0 To appList.Count
            If (name = appList(i).getAName()) Then
                If (name = "Washer") Then
                    s = appList(i).getWUsage() ' !!!This is the line where the execution dies at, nothing after this line is processed and the function call is not completed
                    txtbGPH.Text = s
                End If

                MsgBox("Test 1")
                Exit For

            ElseIf (i = appList.Count) Then
                MsgBox("Appliance could not be found")
            End If
        Next
    End Function

End Class

Answer 1

如果您只想插入一种类型，请使用List(Of X)代替ArrayList：

Dim appList As New List(Of Appliances)

我建议你在方法中声明你的temp var，除非有必要。无论如何，在这种情况下你不需要它，你可以用这种方式添加var：

appList.Add(New Appliances(words(0), Double.Parse(words(1))))

通过这种使用（使用列表），您不需要使用arraylistObj.Item(i).Method()，只需使用常用方法：

s = appList(i).getWUsage()

Answer 2

没关系，我刚才想出来了。我不知道arraylists不是“arraylists”，而是一个集合。我想也许它会像其他面向集合的对象一样，你必须使用.item（i）来访问元素，事实证明是这样。

txtbGPH.text = appList.item(i).getAWusage()

在OP执行的有问题的行执行后，

产生正确的行为和其余代码，并且在被调用函数中设置的断点也是如此。

来自Arraylist元素的函数调用不起作用

2 个答案: